The present invention relates to operation of a computer system, and more particularly to operation of such a system in a pre-boot environment.
When a computer system is turned on, it cannot perform functions desired by a user until it is initialized and is able to communicate with the user. This initialization process generally includes a booting procedure, typically performed by boot-up firmware. The boot-up firmware may be an operating system (“OS”), a portion of the OS, the Basic Input/Output System (“BIOS”), or other software.
The boot-up firmware is typically stored in some form of non-volatile memory and allows a central processing unit (“CPU”) to perform tasks such as initialization, diagnostics, loading the operating system kernel from mass storage, and routine input/output (“I/O”) functions. The boot-up firmware may be stored in erasable programmable read only memory (“EPROM”) or flash semiconductor memory.
In this pre-boot environment, typically few or no security measures are available (all code runs in primitive, ring0 physical mode), nor is there an ability to store a secret in the pre-boot environment. Further, when the OS environment is entered from the pre-boot environment, there is no ability to establish a so-called root of trust from the pre-boot environment to the OS environment. Such a root of trust may be desirable for a Trusted Computing Platform (TCP) in accordance with the Trusted Computing Platform Alliance (TCPA) Main Specification Version 1.16, published Feb. 22, 2002, to provide reliable information about itself and its current software processes, and provide attestation to operation of its software processes.